Dash-pot.



, PATENTED JULY 31, 1906. w. R.]WHITNEY.

DASH POT. APPLIOATION FILED 00113, 1905 Mtnasoea rim NORRIS PETERS co., wasnmarau. n. c

UNITED ZsrATEs WILLIS R. "WHITNEY, or SCHENECTADY; NEW YORK, ASSIGNQR 'ao snu- PATENT 'ERAL ELECTRIC COMPANY, A CORPORATION QF NEW YORK.

' DASH-For.

.To all whom it=may concern.-" 7

*Beiit known thaflL'W-ILLIS R. WHITNEY, a citizen of the United "States, A residing at Schenectady, 'countyof Schenectady, State ofNew Yorkyhaveinvented certain new. and useful Improvements in Dash-Pots, of which the followingis a specification.

This invention :relates .to pistons ..or the 1 like to be. used in connection with cylinders,

and has forlits object ithe improvement of devicesof this character, so asito render them reliable and efficient under. all conditionsand at-the-sametime cheap and durable.

More specifically, the invention .relates to 'andmprovement'in.pistons-for usein. connection-with-retardin .devices commonly known as "dash-pots.

. it is essential in order toobt ain -a longand uniform :time interval that-the'piston have heretofore been unreliable, since the differ-' a snug running .fit in the cylinder With uniform conditions :it isznot a difficult matterto make a cylinder and piston having a satisfactory fit. In practice, however, the conditions are constantly changing,-. due principally to changes of temperature. Upon a fall of temperature these dash-pots have ence in the contraction and-expansion of the metals. forming the cylinder and the piston causes them to stick. This matter is par ticularly troublesomein the case of dash-pots for use in arc-lamps, where .a particularly uniform and reliable retarding device is reuired. Moreover, it is not sufficient that -t e expansion and contraction of the piston and cylinder be the same. Some provision must be made for lubrication, especially in the case of air dash-pots.

In carrying out my invention I provide a piston which is composed of substantially the same material as the cylinder, so as to give the same expansion coefi icients. In addition to this I provide a self-lubricating bearing-surface between the piston and the cylinder. In this manner. I provide against the sticking of the parts, due to the unequal expansion and contraction, and also provide for constant and uniform lubrication.

My invention further consists in the features of construction and the arrangement and combination of elements hereinafter set forth, and particularly pointed out in the claims annexed .to and forming apart of this application.

. :Specificationof Letters Patent.

. Application filed Oetober'13,1-905. SerialNo 2 82,54O.

" 11 devices of this-character EBatentediJIulylfl1,1905.

. i i :In the drawings, :Figure :1 is .a sectional -.view. of. a dash-.potsembodying my invention.

isa view 0 one of'the-split'rings.

. Referring; totthezdrawmgs, :10- isQ-ai cylinder,

' preferablyof; some uwell-known s-metal, -.such

as brass, open at one end .for the insertionsof the ,piston f1 1 l .Theparticular construction of-this cylinderjforms noxpartiof my-invention and maybe any well-lmown.type. sIn the construction shown ethe cylinder is: closed at Fig. 2isa view-ofthepiston.ofithedashapot, the bearin -.rings being.in=seetion;;and.Fig. 3.

metallic parts these bearing-surfaces must be made yielding. This I accomplish by having the rings split, as at 16, so that the elasticity of the-rings will allow them to contract and expand, as may be necessary.

In the drawings I have shownthree split rings having the splits staggered to prevent leakage. The rings are originally made with an outer diameter a trifle smaller than the diameter of the plunger with which they are I to be used. The rings are then split in any desired manneras, for instance, by being cut partially through from the outside and then ruptured by forcing atight-fitting core 'into them. The rings are then assembled in a slightly extended or expanded form upon the core of the plunger, the amount of the expansion being just sufiicient to make a snug running fit in the cylinder.

It will thus be seen that I have provided a dash-pot which will be absolutely reliable at all temperatures. The dash-pot and the plunger being of the same or similar metals will expand equally and the graphite will furnish the lubricant. I have made the lubri- 9 inner diameter of the cylinder and the inner diameter of the rings smaller than the outer eating-surface expansible, so as to allow for these variatlons in a very simple manner, it

.being possible to slip the rings over the flange lars to What I have shown and described beyond the scope of the'claims annexed hereto.

. What I claim as new, and desire to secure by Letters Patent of the United States, is .1. A dash-pot piston having a yielding bearing-surface of self-lubricating material. 2. A dash-pot piston having a rigid body portion and a yielding bearing-surface of self-lubricating material. 20.

.portion and a resilient bearing-ring of self- 3. A dash-pot piston having a rigid body lubricating material.

4. A dash-pot piston comprising a metallic .bodyportion and a yielding bearing-ring of graphite.

5. A dash-pot comprising a cylinder and a piston having substantially the same expansion coeflicients, one of said parts having a self-lubricating bearing-surface. 6. A dash-pot comprising a metallic cylinder and a piston therefor having a metallic body portion and a yielding self-lubricating bearing-ring.

7. A dash-pot comprising a metallic cylinder and a piston therefor having a rigid body portion and a bearing-surface composed of self-lubricating split rings.

8. A dash-pot comprising a metallic cylinder and a piston therefor having a metallic body portion and a self-lubricating bearingsurface, said metallic parts having substantially the same expansion coefficients.

9. A dash-pot comprising a metallic cylinder and a piston therefor having a metallic body portion and a yielding self-lubricating bearing-surface, said metallic parts having substantially'the same expansion ooeflicients.

10. A dash-pot comprising a metallic cylinder and a piston therefor having a metallic body portion and a graphite bearing-surface, said metallic parts having substantially the same expansion coeflicients.

11. A dash-pot comprising a metallic cylinder and a piston therefor having a rigid metallic body portion and a bearing-surface composed of self-lubricating split rings, said metallic parts having substantially the same expansion coefiicients.

12. A dash-pot comprising a metallic cylinder and a piston therefor having a solid metallic body portion and a bearing-surface composed of staggered graphite split rings, said metallic parts having substantially the same expansion coefficients.

In Witness whereof I have hereunto set my hand this 11th day of October, 1905.

WILLIS R. WHITNEY. Witnesses:

BENJAMIN B. HULL, HELEN ORFORD. 

